1. Field of the Invention
The present invention relates to a probe card coplanarity inspection tool, and more particularly, to a coplanarity inspection device adapted for printed circuit boards, with such a mechanism the manner using a round probe card for inspecting the flatness of printed circuit boards can be standardized.
2. Description of Related Art
Generally speaking, determination on good or bad round probe cards is based on the coplanarity of printed circuit boards. The so-called “coplanarity” refers, in short, to an overall level of the flatness of printed circuit boards. For example, in case the coplanarity of the printed circuit board is within a specific standard value, the probe welded to the printed circuit board will have a relatively good orthogonality on the printed circuit board and a good parallelity between the probes. The probe card made according to the printed circuit board will result in a probe having a good ground contact with the touched location of a measured element so as to obtain accurate measurement data. However, in case the coplanarity of the printed circuit board exceeds the specific standard value, the probe card made according to the printed circuit board cannot be sure of a good contact with the touched location of the measured element, and so accurate measurement data cannot be assured.
A conventional manner for measuring the coplanarity of a printed circuit board is that a granite base is taken as a horizontal basis, and a circular printed circuit board is placed thereabove, then a feeler gauge is used to measure to what extent the printed circuit board is curved against the granite base so as to calculate the coplanarity thereof. Because the measurement is proceeded through touching the printed circuit board with human hands, the coplanarity data thus obtained is questionable due to interference by man's factor. Therefore, it is an urge to develop a standardized measurement for a coplanarity inspection mechanism using a round probe card to accurately measure the flatness of printed circuit boards.